Singaporean election system Interesting

I have difficulties in understanding the Singaporean election system: "The People’s Action Party (PAP) was returned to power with a credible 60.1 per cent of the vote in a promise of economic growth and political stability in the next five years. With 81 out of the 87 seats in Parliament, the Government will enjoy a strong electoral mandate on which to plan and pursue policies decisively for the long term."

How do 60.1% of the vote translate to 81 out of the 87 seats in Parliament?

81 of out of 87 means more than 90%, doesn't it?

The system must have some rather interesting features of some sort of biases to produce these results. Or the election was distributed in a way that channelled the results to favouring the PAP.